1. Field of the Invention
The present invention relates to an environment recognition device and an environment recognition method for recognizing a target object based on a luminance of the target object in a detection area.
2. Description of Related Art
Conventionally, a technique has been known that detects a target object such as an obstacle including a vehicle and a traffic light located in front of a subject vehicle for performing control to avoid collision with the detected target object and to maintain a safe distance between the subject vehicle and the preceding vehicle for example, Japanese Patent No. 3349060 (Japanese Patent Application Laid-Open (JPA) No. 10-283461)
Further, in such techniques, there is a technique that performs more advanced control. Specifically, it not only specifies a target object simply as a solid object, but further determines whether the detected target object is a preceding vehicle that is running at the same speed as the subject vehicle or a fixed object that does not move. In this case, when the target object is detected by capturing an image of a detection area, it is necessary to extract (cut out) the target object from the captured image before specifying what the target object is.
For example, when the captured image is a color image, there may be a method for grouping pixels with a similar luminance (color) and extracting the pixels as a target object.
When it is raining or snowing, the captured image is such that light of a target object such as a traffic light is diffused due to water droplets deposited onto a front window, or streak caused by cleaning the water droplets. Therefore, if a plurality of pixels with similar color characteristic is simply grouped, the target object from which emitted light is diffused as described above might be recognized to be larger than the actual size thereof.